In the same district, invariably keeping at the bottom of the valleys, is found the Columbian thorn-bill. It does not even mount, as do many humming-birds, to the tops of the trees, but seeks its food among the low, flowering shrubs. It is of a golden green colour on the upper parts, and of a dull green below; except on its curious tuft, which hangs from the chin, and is of a light green at the base, and a purple-red towards the points. The wings are of a purple-brown hue, as is the tail, with a bronzed gloss, while the under tail-coverts are brown-yellow. It is curious that the hen, though in other respects like the male, has no beard. BLACK WARRIOR. At the height of 13,000 feet above the ocean is found a curious bird, which, from the pointed plume crowning the top of its head, and the long beard-like projection from its chin, is very appropriately called the helmet-crest or black warrior. It inhabits regions immediately below the line of perpetual snow, where we should least expect to find so delicate a creature. Its food it gathers from the thinly scattered shrubs projecting from the ledges of rock near the snow. Its flight is swift, but very short. When launching itself from the lofty height on which it is perched, it flies obliquely downwards, uttering at the same time a plaintive, whistling sound. It is more sedate in its habits than its brethren, nor does it seem to partake of their joyous spirit. The head and neck of the male are black, with a line running along the centre. The long beard is white, and round the neck and back of the head is a broad band of white. The upper surface of the body and the two central feathers of the tail are bronzed green, the others being of a warm reddish bronze. Its length is a little over five inches. The female is chiefly brown, and possesses no beard or helmet-like plume; it is also considerably smaller. THE SICKLE-BILL. In the humming-birds, we see the same perfect adaptation of their construction to their peculiar wants which is found throughout the whole animal creation. This is beautifully exhibited in the sickle-bill, which is occasionally found in Bogota. Its bill is very short and sharply curved, in order that it may enter the short, curved flowers of that region. It is generally of a duller hue than most of its tribe. Its head and small crest are blackish-brown, each feather having a spot of buff on its tip. The upper part of the body is of a dark, glossy green, slightly touched with buff. The under part is a brownish-black, with a few buff streaks upon the throat and breast. It is about four and a half inches long. MARS' SUN-ANGEL. Mr Gould describes the Mars' sun-angel as among the most beautiful of the genus Heliangelus inhabiting the northern end of the Cordilleras.